The statement means that no further flood threat exists, and it is safe for people to move around.

The Committee says those whose homes were not damaged or destroyed can return home, while those who have no place to return to should remain in evacuation centres.

The statement comes as the chairman of the Solomon Islands National Disaster Council says Honiara needs reconstruction, not rehabilitation, in the wake of deadly flash floods.

Permanent secretary Melchoir Mataki says that infrastructure needs to be rebuilt, not just repaired.

"At this stage what we need is reconstruction - mere rehabilitation will not work in the long term," he said.

"It will be just a band-aid.

"What we need is reconstruction of roads and other infrastructure, bridges for example, that need to be done."

Honiara and the whole of the island of Guadalcanal have been declared a disaster zone after torrential rain caused massive flooding, loss of life and loss of homes.

Mr Mataki says many of those who lost their homes lived on a flood plain, where they were not supposed to build.

"So they have naturally increased their risk, the risk of them being flooded," he said.

"But I think the issue has been they have not experienced flooding of such magnitude in the past, so they thought, probably, that it is still safe to build around there.

"The government is looking into ways of assisting them to recover from the disaster they have faced, but we certainly have a lot of constraints in terms of resources and capability."

On Tuesday, Australia's Foreign Minister Julie Bishop announced Australia will increase its aid package to $3 million, with most of the assistance to address immediate needs such as safe drinking water, shelter, food and sanitation.

Disease fears

Fears are also growing of an outbreak of disease, with infrastructures damage, including the sewerage system and water supplies, badly damaged or destroyed.

The National Disaster Management Office says dysentery, malaria, dengue fever and other diseases related to poor sanitation are all a real risk.

Solomon Islands head of the Save The Children Fund Graham Kenna says the flooding will increase the damage from diseases already spreading through the country.

"There is a desperation to get these people away from the evacuation centres and get them settled somewhere which is more permanent for them," he said.

"Two days ago there was the start of diarrheal disease and... conjunctivitis.

"Prior to the flooding there was the start of a dengue fever outbreak, which we know is going to be a lot worse once the place starts to dry out."

The Solomon Islands Water Authority says 40 per cent of Honiara is still cut off from the water supply, including many evacuation centres.

"A lot of the water sources would have been inundated with dirty water," Mr Mataki said.

"So our concern here is not just with water, clean water availability in Honiara but also out in the provinces, for which we would definitely need support and assistance to ensure that our people have access to clean, safe, drinking water."